Time to bin it and buy a new one as after a while they become corrupted for which there is no reliable fix.
I always keep a couple of spares in readiness for when that happens.
Trying or hoping to revive it is pointless, as even if you succeeded it wouldn't be reliable, and do you really want to risk using an unreliable card? It's not as though as though they cost a fortune to replace.
Hello, I'm Jewel with Kingston Technical Support and would like to offer our assistance. If used in an Android 4.1 or later phone, you may have been affected by a known issue that caused different microSDHC cards to stop being recognized as you described. This issue has since been resolved within our microSDHC cards and as we stand by all our products the card can be replaced under it's lifetime warranty. Please call us at 1-800-435-0640 (USA and Canada only) M - F 6am - 6pm PT and I or another available Technician will assist you. Please be sure to have the part in question on hand when you call.
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